High Repetition Rate Gain-Switched Thulium Fiber Laser With an Acousto-Optic Modulator

We demonstrate a stable gain-switched thulium fiber laser pumped with an acousto-optically modulated Er, Yb co-doped fiber laser at 1.56 μm. The laser produced 1850 nm pulses with 2.5 μJ pulse energy and 75 ns pulsewidth at a repetition rate of 500 kHz, resulting in a maximum average output power of 1.32 W and slope efficiency of 54.7% with respect to absorbed pump power. The dependence of laser output characteristics on the pump power and repetition rate was presented and discussed. Repetition rate of gain-switched pulses was tuned continuously from 68 kHz to over 1 MHz at the maximum pump power-level of 8 W. The broad tuning range of pulse repetition rate makes this laser suitable for various applications.